THE BASICS OF EQUINE DENTISTRY Preventative Medicine Course UMN College of Veterinary Medicine Alli Linn, DVM Alli Linn, DVM Main Points ▪ Brief history of equine dentistry ▪ Terminology ▪ Anatomy Review ▪ Why do horses need dental care? ▪ Appointment Basics ▪ Equipment Needs ▪ Dentistry Basics ▪ Complications and Considerations Witchtree Training Center History of Equine Dental Care ▪ Evidence for ethical medical treatment of humans and animals dates back to at least 2200 BCE. ▪ Horses were domesticated approximately 5000 years ago and by 300-400 BCE texts had been written about horsemanship. ▪ These documents contained information about aging horses based on their teeth, eruption times, and diseases of the teeth. ▪ Practices that would be considered barbaric and unethical today were commonly performed from the 1500s to the 1700s. ▪ Saws, chisels, and hammers were often used to correct malocclusions, and horses often sustained serious, sometimes fatal, injuries from the practice of dentistry. ▪ Dentistry was usually performed by farriers or other lay people. ▪ More formal veterinary training throughout the 1800s and 1900s advanced the information and tools available and made the practice safer for practitioners and patients. ▪ Dentistry as we know it today began to develop in earnest in the 1970s, with the development of power floats, improved sedative drugs, and more research into equine specific dental topics. http://www.avdc.org/Horse_dental_examination.jpg Basic Terminology – Why is it “floating” teeth? ▪ Today, there are many terms used to describe various features of equine dental care. By far the most common and most used by clients is “floating.” ▪ “Floating” is a term from the carpentry/masonry industry which means “leveling.” ▪ In the equine dentistry world, floating refers to the most basic examination and adjustment that is performed on the teeth. This generally includes removing sharp points and small malocclusions (abnormalities of bite) to make the horse more comfortable. ▪ Dental prophylaxis (or a “dental prophy”) is a term used more commonly in small animal medicine but would be an appropriate term to replace “floating.” ▪ Other terms that are sometimes used interchangeably with floating are dental adjustment or dental equilibration, although these terms, particularly equilibration, should be reserved to describe the correction of more extensive dental problems or malocclusions. ▪ Odontoplasty may also be used to refer to extensive adjustments of malocclusions. Alli Linn, DVM ▪ Performance dentistry involves specific adjustments or procedures designed to help the horse accommodate a bit or other tack items. Anatomy Overview ▪ Horses are highly adapted to their grazing lifestyle. ▪ They prehend food with their front incisors. ▪ Large cheek teeth arcades (premolars and molars) have a rough occlusal surface that acts as a grinding surface for fibrous feeds. ▪ The horse’s dental formula is 2(I3/3, C 0-1/0- 1, PM 3-4/3-4, M 3/3) ▪ I = Incisors; C = Canines; PM = Premolars; M = Molars – top number is upper arcade, bottom number is lower arcade ▪ Mares may or may not have canines, and are usually small if present. ▪ Horses may or may not have the first PM (the “wolf tooth”). Wolf teeth are much more common on the upper arcades. http://www.myhorsedentist.com/Diagrams/Equis%20Magazine%20'06.jpg Anatomy Overview http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/horsepage.html http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/horsepage.html http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/horsepage.html http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/horsepage.html Naming of Teeth – Modified Triadan System ▪ The modified Triadan numbering system is used to identify individual teeth in the horse’s mouth. ▪ The mouth is first divided into 4 quadrants, starting at the top right with 100 and moving clockwise to the bottom right with 400. ▪ From there, the 11 teeth in each quadrant are numbered 1-11, starting with the central incisor and moving back to the last cheek tooth. http://www.pro- ▪ This system allows veterinarians to talk equinedentistry.com/equine_veterinary_education_pap er_files/image017.jpg to each other in a language everyone understands. http://files.dorset-horse-watch.webnode.com/200000037- 07c1909b1f/Noggin%20head%20front.jpg Naming of Teeth – Modified Triadan System http://www.equine-dentist-scotland.co.uk/wp-content/uploads/2013/02/horse-skull.jpg http://www.equine-dentist-scotland.co.uk/wp-content/uploads/2013/02/horse-skull.jpg Anatomy Overview ▪ Equine teeth are hypsodont (meaning “high crowned”) and erupt continuously over their lifetime. ▪ Teeth are originally very long and wear out over the life of the horse due to their fibrous diet (generally between 20-30 years old). Nearly Expired (Worn Out) Teeth Young Horse Teeth Clinical Crown Reserve Crown Roots http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/horsepage.html http://www.animaldental.com.au/images/image2.jpg Anatomy Overview ▪ Hypsodont teeth are comprised of 3 primary tissues with a very rough occlusal (chewing) surface. ▪ 1. Enamel: This is the hardest tissue in the body and is responsible largely for grinding fibrous feedstuff. ▪ 2. Dentin: This is a softer calcified tissue which wears faster than enamel and acts as a cushion for the brittle enamel. ▪ 3. Cementum: This tissue is similar to dentin in that it is softer than enamel. It cushions enamel and also helps anchor the tooth to the periodontal ligament. ▪ Cheek teeth on the maxillary arcade have 2 infundibulae, which are deep infoldings of enamel filled with cementum in the center of the teeth. Mandibular cheek teeth do not have infundibulae. ▪ Equine cheek teeth have either 5 or 6 pulp horns each. Anatomy Overview Maxillary Cheek Tooth Mandibular Cheek Tooth Buccal (toward lip) Infundibulae Lingual (toward tongue) Enamel (Red) Cementum (Green) Buccal Palatal (toward palate) Dentin (Blue) (surrounding pulp horns) http://animaldiversity.ummz.umich.edu/media/skul http://www.zoodent.com/images/photos/cli ls/equus/e._caballus/164990.um2.jpg nical/equids/cheek_link.jpg Key Reasons Horses Require Dental Care ▪ Remove sharp points to prevent injury to oral soft tissues ▪ Help improve mastication and digestion of feedstuff ▪ Prevent gastrointestinal issues ▪ Prevent weight loss due to inadequate intake or digestion ▪ Prolong tooth life (when performed regularly and correctly) ▪ Correct malocclusions that put extra stress on jaws or abnormal teeth ▪ Allow better comfort in all horses, particularly performance horses http://www.theanimalcenter.net/siteimages/horse%20mouth%20float.jpg ▪ Catch problems early ▪ Including: Periodontal disease, tooth root abscesses, fractured teeth, sinus infections, etc. The Appointment ▪ At the time of the appointment, a thorough history and physical exam should be performed on every patient. ▪ Information like age and use of the horse, diet, turnout situation, and potential vices or problem behaviors may be very important considerations for the horse’s dental health. ▪ Body condition score is a significant physical exam parameter when assessing a horse before a dental procedure. ▪ Other physical examination parameters such as muscle development, attitude, coat condition, and any abnormalities in the respiratory system, gastrointestinal system, or head may provide clues to a dental issue. Witchtree Training Center The Appointment ▪ Restraint and Safety: ▪ Horses should be properly restrained with a halter and lead rope by a competent and attentive handler (aka: no cell phones!). Even when sedated, horses are capable of kicking, rearing, and breaking free. ▪ Whenever possible, DO NOT have the client hold the horse for dentistry due to liability issues. ▪ The procedure should be performed in a quiet area safe for a horse to stand. A stall or bathing area are the most commonly used, although other veterinarians will design specially made stocks or http://www.news.cornell.edu/sites/chronicle.cornell/files/EquineDentistry.jpg trailers to work in. ▪ A wash stall, etc. doubling as a storage area could pose a safety hazard to the veterinarian, the client or other personnel, and the horse. http://www.equusvet.com/0i/0e-ii/lrg-dentistry_002.jpg Witchtree Training Center http://www.tntequine.com/photos/teeth-float.jpg The Appointment ▪ Horses should be sedated for all dental procedures. Many practitioners will do a cursory unsedated look inside the horse’s mouth with a headlamp or flashlight before recommending a sedated exam and float. Be cautious when using this technique, as this often grossly underestimates pathology and can be dangerous. ▪ The horse should be positioned before or immediately after sedation. Many practitioners will back the patient into a corner, although others need them in the doorway of a stall to use a particular type of dental halter. ▪ Remember, horses can be significantly ataxic after sedation, so positioning them properly before this is very important. Make sure the horse’s limbs are http://www.regardinghorses.com/wp- content/uploads/2009/07/ace-sedated.jpg properly underneath them by gently asking the horse to adjust their position before they become very Witchtree Training Center sedate. NEVER pick up the limbs of a very sedate horse, as they may lose their balance and fall. The Appointment ▪ Commonly used sedatives include: ▪ Alpha-2 Agonists: ▪ Xylazine (0.2-1.1mg/kg IV) Improper and unsafe ▪ Detomidine (0.005-0.02 mg/kg IV) technique ▪